Patent Application
20070049305
1. Field of the Invention
This invention relates generally to telecommunications, and, more particularly, to wireless communications.
2. Description of the Related Art
In the field of wireless telecommunications, such as cellular telephony, a system typically includes a plurality of base stations (or NodeBs in 3GPP (3rd Generation Partnership Project) terminology) distributed within an area to be serviced by the system. Various mobile devices (or User Equipment-UE in 3GPP terminology) within the area may then access the system and, thus, other interconnected telecommunications systems, via one or more of the base stations. Typically, a mobile device maintains communications with the system as it passes through an area by communicating with one or more base stations, as the mobile device moves. The process of communicating with multiple base stations simultaneously is commonly referred to as a soft nandoii and it may occur relatively often if the mobile device is moving rapidly. The mobile device may communicate with the closest base station, the base stations with the strongest signal, the base stations with a capacity sufficient to accept communications, etc.
When the mobile device is in soft handoff, multiple base stations are transmitting signals to the mobile device. For design complexity reasons, these signals from different base stations should arrive at the mobile device within a fixed time window. The size of the window directly impacts the mobile device cost, complexity, power consumption, etc. Due to mobility of the mobile device and/or asynchronous base stations, the arrival time of signals from different base stations is constantly changing, and it happens frequently that signals from some base stations fall outside the predefined mobile device receive window (the window position is locked to one base station at a time), resulting in signal losses, poor call quality and sometimes even dropped calls. Therefore a timing adjustment feature is introduced by 3GPP for DPCH (Dedicated Physical Channel) so that the mobile device can signal to the base station to adjust the downlink signal timing backward or forward by a preselected amount to ensure that the cell that is drifting away will be received inside the mobile device reception window. The timing adjustment for the new E-DCH (Enhanced Dedicated Channel) related channels, such as E-HICH (E-DCH HARQ Indicator CHannel) and E-RGCH (E-DCH Relative Grant Channel) are, however, not defined.
The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above. The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an exhaustive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to discussed later.
In one aspect of the instant invention, a method is provided for adjusting timing of transmissions within a wireless communications system. The method comprises receiving a request for a timing adjustment and adjusting timing of a first downlink channel in a first frame. The timing adjustment is then applied to a second downlink channel in a second frame associated with the first frame.
The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions may be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but may nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
Turning now to the drawings, and specifically referring to
In one embodiment, a plurality of the base stations 130 may be coupled to a Radio Network Controller (RNC) 138 by one or more connections 139, such as T1/EI lines or circuits, ATM circuits, cables, optical digital subscriber lines (DSLs), and the like. Although one RNC 138 is illustrated, those skilled in the art will appreciate that a plurality of RNCs 138 may be utilized to interface with a large number of base stations 130. Generally, the RNC 138 operates to control and coordinate the base stations 130 to which it is connected. The RNC 138 of
The RNC 138 is also coupled to a Core Network (CN) 165 via a connection 145, which may take on any of a variety of forms, such as T1/EI lines or circuits, ATM circuits, cables, optical digital subscriber lines (DSLs), and the like. Generally the CN 165 operates as an interface to a data network 125 and/or to the PSTN 160. The CN 165 performs a variety of functions and operations, such as user authentication, however, a detailed description of the structure and operation of the CN 165 is not necessary to an understanding and appreciation of the instant invention. Accordingly, to avoid unnecessarily obfuscating the instant invention, further details of the CN 165 are not presented herein.
The data network 125 may be a packet-switched data network, such as a data network according to the Internet Protocol (IP). One version of IP is described in Request for Comments (RFC) 791, entitled “Internet Protocol,” dated September 1981. Other versions of IP, such as IPv6, or other connectionless, packet-switched standards may also be utilized in further embodiments. A version of IPv6 is described in RFC 2460, entitled “Internet Protocol, Version 6 (IPv6) Specification,” dated December 1998. The data network 125 may also include other types of packet-based data networks in further embodiments. Examples of such other packet-based data networks include Asynchronous Transfer Mode (ATM), Frame Relay networks, and the like.
As utilized herein, a “data network” may refer to one or more communication networks, channels, links, or paths, and systems or devices (such as routers) used to route data over such networks, channels, links, or paths.
Thus, those skilled in the art will appreciate that the communications system 100 facilitates communications between the mobile devices 120 and the data network 125 and/or the PSTN 160. It should be understood, however, that the configuration of the communications system 100 of
Unless specifically stated otherwise, or as is apparent from the discussion, terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical, electronic quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system's memories or registers or other such information storage, transmission or display devices.
Referring now to
The interface unit 200, in the illustrated embodiment, controls the flow of information between the base station 130 and the RNC 138 (see
The mobile device 120 shares certain functional attributes with the base station 130. For example, the mobile device 120 includes a controller 250, an antenna 255 and a plurality of channels and processing circuitry, such as a DPCH processing circuit 260, an E-HICH/E-AGCH/E-RECH processing circuit 270, a HS-SCCH/PDSCH processing circuit 280, and the like. The controller 250 generally operates to control both the transmission and reception of data and control signals over the antenna 255 and the plurality of channels 260, 270, 280.
Normally, the channels in the mobile device 120 communicate with the corresponding channels in the base station 130. Under the operation of the controllers 210, 250, the channels and their associated processing circuits 220, 260; 230, 270; 240, 280 are used to effect a controlled scheduling for communications from the base station 130 to the mobile device 120.
Typically, operation of the channels and their associated processing circuits 260, 270, 280 in the mobile device 120 and the corresponding channels and processing circuits 220, 230, 240 in the base station 130 have been subframe (2 ms), frame (8 ms) or frame (10 ms) operated.
Turning to
Operation of the instant invention may be appreciated by reference to the flow chart of
Turning now to
Transmissions within the system are divided into a series of units typically identified by a System Frame Number (SFNi) and a subframe number (sub). In one embodiment of the instant invention shown in
In the instance where the timing change causes a delay in transmitting the downlink channels, there are several choices. For example, the base station 130 may accomplish the delay by not transmitting (DTXing) for two subframes and then transmitting the next subframe 508 (HICH for SFNi-1 sub2), as shown at 502B. This can allow the mobile device 120 to have the same behavior without taking into account the adjustment type (timing delay/timing advance/no change), i.e. not transmitting in SFNi-1 subframe 1. Alternatively, may the base station 130 accomplish the delay by not transmitting (DTXing) for 1 subframe and transmitting the previous subframe 506 and the next subframe 508 (HICH for SFNi-1 sub2), (not shown). This can allow the mobile device 120 to transmit all subframes. This allows more data to be transmitted while adding more complexity to the mobile.
In the instance where the timing change causes no change in transmitting the downlink channels, there are at least two possible behaviors. For example, the base station 130 does not transmit (DTXes) only the subframe 506 (HICH for SFNi-1 sub1) and then transmitting the next subframe 508 (HICH for SFNi-1 sub2), as shown at 502C. This can allow the mobile device 120 to have the same behavior without taking into account the adjustment type (timing delay/timing advance/no change), i.e. not transmitting in SFNi-1 subframe 1. The base station 130, as well as, the mobile device 120, transmit all subframes and behave as if no timing adjustment occurred on the DL DPCH channel in SFNi (not shown).
Those skilled in the art will appreciate that it may in some embodiments be useful to immediately apply an adjustment to the downlink channels, as shown in the embodiment of
Operation of the instant invention may be appreciated by reference to the flow chart of
Those skilled in the art will appreciate that the various system layers, routines, or modules illustrated in the various embodiments herein may be executable control units. The control units may include a microprocessor, a microcontroller, a digital signal processor, a processor card (including one or more microprocessors or controllers), an FPGA, an ASIC (Application Specific Integrated Circuits), a ASSP (Application Specific Standard Product) or other control or computing devices. The storage devices referred to in this discussion may include one or more machine-readable storage media for storing data and instructions. The storage media may include different forms of memory including semiconductor memory devices such as dynamic or static random access memories (DRAMs or SRAMs), erasable and programmable read-only memories (EPROMs), electrically erasable and programmable read-only memories (EEPROMs) and flash memories; magnetic disks such as fixed, floppy, removable disks; other magnetic media including tape; and optical media such as compact disks (CDs) or digital video disks (DVDs). Instructions that make up the various software layers, routines, or modules in the various systems may be stored in respective storage devices. The instructions when executed by the control units cause the corresponding system to perform programmed acts.
The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. Consequently, the method, system and portions thereof and of the described method and system may be implemented in different locations, such as the wireless unit, the base station, a base station controller and/or mobile switching center. Moreover, processing circuitry required to implement and use the described system may be implemented in application specific integrated circuits, software-driven processing circuitry, firmware, programmable logic devices, hardware, discrete components or arrangements of the above components as would be understood by one of ordinary skill in the art with the benefit of this disclosure. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.
